topic 5 gen-iii systems from the initial requirements to ... library/20110201.pdf · dr. blair p....

Dr. Blair P. Bromley, Atomic Energy of Canada Limited (AECL) – Chalk River LaboratoriesDr. Blair P. Bromley, Atomic Energy of Canada Limited (AECL) – Chalk River Laboratories

Aug. 25 – Sept. 3, 2010

TOPIC 5

Gen-III Systems – From the Initial Requirements to the

Designers’ Choices

********

5.4. Advanced Heavy Water Reactors (AHWRs)

Main Lecture

Dr. Blair P. Bromley

Atomic Energy of Canada Limited (AECL) – Chalk River Laboratories

Building 889, Room 130, 1 Plant Road, Chalk River, Ontario, Canada, K0J 1J0

Phone: 613-584-8811 ext. 43676, e-mail: [email protected]

The 2010 Frédéric Joliot & Otto Hahn Summer School

August 25 – September 3, 2010 Aix-en-Provence, France

www.fjohss.eu

1


Aug. 25 – Sept. 3, 2010

Schedule (Day 1)

Day 1

Physics background.

Heavy water separation (optional, see slides/notes offline).

Design options for HWR‟s.

HWR characteristics.

Design components (focus on CANDU-type)

• CANDU (CANada Deuterium Uranium)

Control devices.

Fuel cycles, thorium (optional, see slides/notes offline).

CANDU-PHWR features.

2


Aug. 25 – Sept. 3, 2010

What We Won’t Cover

See supplementary presentations for further reading.

R&D Activities for HWR „s - Supplement 1

Types of Measurements/Testing.

Heavy Water Research Reactors and Critical Facilities.

International Participation (Past and Present).

Present R&D Efforts and Needs for HWR‟s.

Additional Information – Supplement 2

Alternative Deuterium-Based Moderators

Alternative Uses for D2O

Alternative Coolants

International Participation in HWR Technology

• Various HWR Prototypes.

Alternative HWR Reactor Designs Proposed.

3


Aug. 25 – Sept. 3, 2010

Goals

Better understanding and appreciation of heavy water reactors.

Motivation.

How it works.

Design features.

Physics issues, engineering issues.

What you can do with HWR‟s.

Long term prospects

Implications for future.

4


Aug. 25 – Sept. 3, 2010

Reactor Physics Considerations

Goal is to sustain fission reactions in a critical assembly using

available fissile (and fertile) isotopes.

Fissile (e.g., U-235, U-233, Pu-239, Pu-241)

Fertile (e.g., breed Pu-239 from U-238, U-233 from Th-232)

Fissionable (eg. U-238, Th-232 at high energies)

• Also: isotopes with low thermal fission cross sections:

o Pu-238, Pu-240, Pu-242, Am-241, Am-243, Cm-244, and other MA‟s.

Fission cross section for various isotopes.

Thermal spectrum: ~ 500 barns to 1000 barns.

Fast spectrum: ~ 1 barn to 10 barns.

Minimize enrichment requirements.

Cost.

Safety (storage/handling).

Incentive to use thermal reactors.

5


Aug. 25 – Sept. 3, 2010

Isotopes for Moderation

H, D, 7Li, Be, C – Scatter Cross Sections

Hydrogen highest.

6


Aug. 25 – Sept. 3, 2010

Isotopes for Moderation

H, D, 7Li, Be, C – Capture Cross Sections

Deuterium lowest.

7


Aug. 25 – Sept. 3, 2010

Options for Moderator

Hydrogen-based moderator (H2O, ZrH1.6, CxHy, etc.)

Shortest neutron slowing down distance, but absorption.

Deuterium-based moderator (D2O, ZrD1.6, CxDy, etc.)

Moderating ratio 30 to 80 times higher than alternatives.

Excellent neutron economy possible.

8


Aug. 25 – Sept. 3, 2010

D2O Moderator Advantages

Excellent moderating ratio, ~5,670 >> 71 (H2O)

What does this get you?

Can use lower enrichment (e.g., natural uranium).

• Do not need industrial infrastructure for enrichment of U-235 in U.

Higher burnups for a given enrichment.

• Higher utilization of uranium resources.

Reduce parasitic neutron absorption in moderator.

• Save neutrons, and spend them elsewhere.

o For fission, for conversion.

• Permits use of higher-absorption structural materials.

o High P, High T environments – better efficiencies.

o Materials to withstand corrosive environments.

Thermal breeders with U-233 / Th-232 cycle feasible.

• C.R. ~ 1.0, or higher, depending on design.

It’s all about neutron economy!

9


Aug. 25 – Sept. 3, 2010

D2O Characteristics

Thermal-hydraulic properties similar to H2O.

Abundance: ~0.015 % D2O in water; need to concentrate it.

Purity Required > 99.5 wt%D2O

dkeff/dwt%D2O ~ +10 to +30 mk/wt%D2O (1000 to 3000 pcm/wt%D2O)

Less sensitive for enriched fuel.

1 mk = 100 pcm = 0.001 dk/k

Cost:

~300 to 500 $/kg-D2O; ~200 to 400 $/kWe (using conventional methods).

New technologies will reduce the cost by at least 30%.

Quantity Required

~450 tonnes for CANDU-6 (~ 0.67 tonnes/MWe)

~$150 to $200 million / reactor

Upper limit for D2O-cooled HWR reactors.

• Use of lower moderator/fuel ratio (tighter-lattice pitch) and/or

• Alternative coolants can drastically reduce D2O requirements.

10


Aug. 25 – Sept. 3, 2010

Frederic Joliot

Connection to Heavy Water

http://www.physics.ubc.ca/~waltham/pubs/d2o_19.pdf

Frederic Joliot

Colleagues with Hans von Halban, and Lew Kowarski.

Recognized in 1939 that D2O would be the best moderator.

Helped smuggle 185 kg of HW from Norway to U.K.

D2O eventually went to Canada (along with Kowarski).

If not for WWII, the world‟s first man-made self-sustaining critical

chain reaction in uranium may have occurred in France using D2O

+ natural uranium (NU).

Assisted in developing France‟s first research reactor

ZOE, 1948

Heavy water critical facility.

Inadvertently, Joliot was instrumental in helping set Canada on

course to develop heavy water reactors.

11

http://www.physics.ubc.ca/~waltham/pubs/d2o_19.pdf


Aug. 25 – Sept. 3, 2010

Vessel Design Options for HWR’s

Pressure tubes (PT)

Thick-wall pressure tube is main boundary.

D2O moderator at low T (<100 C), low P (1 atm)

PT sits inside calandria tube (CT).

PT, CT must be low neutron absorber (Zircaloy).

Low-P coolants (organic, liquid metal) may allow thinner PT/CT.

Used in CANDU, EL-4, CVTR designs.

Modular; easier to manufacture.

Pressure vessel (PV)

Thin-walled PT/CT used to isolate fuel channels.

Moderator at higher P (10 to 15 MPa), T (~300 C).

Thick pressure vessel (~20 cm to 30 cm).

Pre-stressed reinforced concrete is an option.

Used in MZFR, Atucha 1, KS-150 designs.

12


Aug. 25 – Sept. 3, 2010

Primary Coolant Options

D2O at 10 to 15 MPa (CANDU, Atucha)

H2O at 10 to 15 MPa (ACR-1000)

Boiling H2O at 5 to 7 MPa (AHWR)

Use previously in SGHWR, FUGEN, Gentilly-1 Prototypes.

Supercritical H2O at 25 MPa (Gen-IV)

SCOTT-R (Westinghouse study, 1960‟s)

CANDU-SCWR (AECL, Gen-IV program)

Other coolants

E.g., gas, organics, liquid metals, molten salt.

See Supplement 2 for additional information.

13


Aug. 25 – Sept. 3, 2010

Primary Coolant Features – D2O

D2O at 10 to 15 MPa (CANDU, Atucha)

Used in conjunction with steam generator.

Low absorption cross section; good neutron economy.

Conventional steam-cycle technology.

Coolant Void Reactivity (CVR)

• Resonance absorption in U-238, U-235 changes with voiding.

• Depends on fuel / lattice design.

o Pin size, enrichment, moderator/fuel ratio, etc.

• May be slightly positive, or negative.

Higher capital costs; minimizing leakage.

Tritium production and handling, but useful by-product.

Water chemistry / corrosion for long-term operation.

Hydriding of Zircaloy-PT.

Efficiencies (net) usually limited to < 34%; 30% to 31% is typical.

14


Aug. 25 – Sept. 3, 2010

Primary Coolant Features: H2O

H2O at 10 to 15 MPa (ACR-1000)

Pressurization to prevent boiling

Tsat ~ 342 C at 15 MPa

Cheaper, lower capital costs.

Conventional steam-cycle technology.

Higher neutron absorption; reduced neutron economy.

Must design lattice carefully to ensure small CVR.

• H2O is a significant neutron absorber, as well as a moderator.

• Use of enriched fuel, poison pins.

Water chemistry / corrosion for long-term operation.

Hydriding of Zircaloy-PT

Net efficiencies usually limited to ~ 34%.

• Higher P and T may allow increase to ~36%.

15


Aug. 25 – Sept. 3, 2010

Primary Coolant Features:

Boiling H2O

Boiling H2O at 5 to 7 MPa (T~264 C to 285 C)

Cheaper, lower capital costs.

Thinner PT‟s feasible; reduced neutron absorption.

Direct steam cycle

• Eliminate steam generator; slightly higher efficiencies.

• Up to 35%.

Neutron absorption in H2O.

Must design lattice carefully to ensure negative CVR.

• Smaller lattice pitch; enriched and/or MOX fuel.

• Moderator displacement tubes.

• More complicated reactivity control system.

Water chemistry / corrosion; hydriding of Zircaloy-PT

Radioactivity in steam turbine.

Demonstrated in SGHWR, Gentilly-1, FUGEN prototypes.

16


Aug. 25 – Sept. 3, 2010

Primary Coolant Features

Super-critical H2O

Supercritical H2O at 25 MPa (T~400 C to 600 C) Similarities to boiling H2O.

Higher efficiencies possible, ~45% to 50%.

Thicker PT‟s required (~ 2; reduced neutron economy).

Severe conditions; corrosive environment

• T~400 C to 625 C.

• High-temp. materials required – reduced neutron economy.

• Use of ZrO2, MgO, or graphite liner for PT.

Design to ensure low CVR

• Enrichment, pitch, pin size, poisons.

Careful design for prevention/mitigation of postulated accidents

• De-pressurization from 25 MPa.

More challenging to design for on-line refuelling.

• May require off-line, multi-batch refuelling (reduced burnup).

• Potential use of burnable neutron poisons, boron in moderator.

17


Aug. 25 – Sept. 3, 2010

HWR Physics Characteristics

Moderator isolated from fuel/coolant.

Kept at lower temp. (< 100 C, for PT reactors).

Physics properties depend on:

Moderator / fuel ratio.

Fuel pin size (resonance self shielding).

Composition / enrichment (U, Pu, Th).

Coolant type (D2O, H2O, gas, organic, liquid metal, etc.).

Reactivity Coefficients.

Fuel temperature comparable to LWR.

• Somewhat smaller in magnitude.

Void reactivity (-ve or +ve ), depending on design.

• Aim for small magnitude.

Power coefficient (-ve or +ve), depending on design.

• Aim for small magnitude, slightly negative.

18


Aug. 25 – Sept. 3, 2010


Special Feature of HWR‟s:

Longer neutron lifetime.

Neutrons diffuse for a longer period of time

before being absorbed (because of D2O)

~ 1 ms vs. LWR (<0.05 ms); ~20 longer.

For U-235 (Beta ~ 6.5 mk, 650 pcm)

= +6 mk (600 pcm) Period ~ 1 sec.

Slower transient (much easier to control).

Extra delayed neutron groups

Delayed neutron fraction (beta) increased.

Photo-neutrons from + D n + H reaction.

Half-life of several photo-neutron precursors >>

delayed neutron precursor (~55 seconds).

Photo-neutron sources with half-lives ranging

from ~2 minutes to ~300 hours.

19


Aug. 25 – Sept. 3, 2010


Conversion Ratio (C.R.).

C.R. = 0.7 to 0.9 (depends on enrichment, parasitic losses).

• U-metal ideal, UC good too, but UO2 more practical in current reactors.

C.R. > 1.0 possible for U-233 / Th-232 thermal breeder.

• Careful design of lattice required to maximize neutron economy.

Burnup of fuel.

Natural U ~ 5 GWd/t to 10 GWd/t (CANDU ~8 GWd/t).

Slightly enriched U ~ 10 GWd/t to 30 GWd/t.

Feasible to use spent LWR fuel / recovered uranium (RU).

• Work in tandem with LWR‟s to maximize energy extraction.

o E.g. use of (RU+DU) = NUE in Qinshan CANDU reactors in China.

• Excellent neutron economy.

o Can burn just about anything.

• Important role for HWR‟s in global fuel cycle.

20


Aug. 25 – Sept. 3, 2010


PT D2O reactors, some unique safety features.

Multiple, independent shutdown systems feasible.

• Shutdown rods.

• Moderator poison injection (B-10, Gd, etc.).

• Low-pressure environment for moderator.

Longer reactor period.

• More time for shutdown systems to work.

Multiple barriers to contain fission products.

• Fuel clad.

• Pressure Tube.

• Calandria Tube.

Large heats sink to dissipate heat.

• D2O moderator, also passive cooling by outer H2O shield tank.

Emergency core cooling (ECC) system, full containment.

21


Aug. 25 – Sept. 3, 2010


Power Density in Core.

Major factor in size/cost of reactor.

• How much concrete are you going to use?

Depends on enrichment, lattice pitch, coolant.

D2O/H2O cooled: ~ 9 to 12 kW/litre

• LWR‟s ~ 50 to 100 kW/litre.

• 15 to 20 kW/litre feasible with tighter lattice pitch

o E.g., ACR-1000, CANDU-SCWR.

Gas-cooled: ~ 1 to 4 kW/litre

• 10 to 15 kW/litre feasible with high pressures (10 MPa)

Organics, Liquid Metal ~ 4 to 10 kW/litre

• 10 to 15 kW/litre feasible.

However, remember: Balance of Plant

Steam generators, steam turbines, condensers take up space.

22


Aug. 25 – Sept. 3, 2010

HWR Operational Characteristics

Heat load to moderator

5% to 6% of fission energy deposited.

Gamma-heating, neutron slowing down (2 MeV 0.0253 eV).

Thermal efficiencies (net)

Depends on choice of coolant, secondary cycle.

Typical: 28% to 32% for CANDU-type reactors.

• Improved for larger, more modern plants.

• Improvements in steam turbines, balance of plant.

• Possible to increase to ~33% to 34%.

32% to 34% feasible for HWBLW-type reactors.

Gas, organic, liquid metal: 35% to 50% (stretch).

• At very high T, potential to use gas turbines (Brayton cycle).

• Or, combined cycles (Brayton + Rankine).

Economies of scale achievable with larger plants.

23


Aug. 25 – Sept. 3, 2010

CANDU-PHWR Design Components

Fuel Bundles (cluster of fuel pins)

Short, small (~10 cm diameter, ~ 50 cm long).

UO2 clad in Zircaloy-4; collapsed cladding.

Graphite interlayer (CANLUB) to improve durability.

Brazed spacers, bearing pads, appendages

• Maintain element separation; enhance cooling

Alternatives (only if coolant type changed):

• Fuel: UC, U3Si

• Clad: SAP (organics) or stainless steel (gas, liquid metal, super-critical H2O)

Pressure Tubes.

Zr-2.5%Nb alloy (corrosion, toughness, strength)

Calandria Tubes.

Zircaloy-2 (rolled joints to fit with steel tube sheet)

Feeders/Headers.

Stainless steel, mechanical rolled joints with PT.

24


Aug. 25 – Sept. 3, 2010

HWR Control Devices

Control rods (stainless steel – SS, etc.)

Shutdown rods (B4C, Cd/Ag/In, SS/Cd, etc.)

Adjusters (flatten flux shape) – Cobalt, SS

Zone controllers

Tubes with liquid H2O used to adjust local reactivity.

Mechanical zone controllers with neutron absorbing material.

Moderator poison options

Boric acid for long-term reactivity changes.

Gadolinium nitrate injection for fast shutdown.

CdSO4, and other compounds.

Moderator level.

Additional reactivity control, for smaller reactors.

Moderator dump tank (for emergency shutdown).

Initial designs; not used in later, larger reactors.

E.g., NPD-2, KANUPP.

25


Aug. 25 – Sept. 3, 2010

CANDU Reactor Technology

CANada Deuterium Uranium (CANDU)

D2O Moderator (~70 C, low pressure) in calandria.

D2O Coolant (~10 MPa, 250 C – 310 C)

Pressure Tubes, Calandria Tubes

28.58-cm square lattice pitch

Natural uranium fuel (UO2) in bundles

37-element (CANDU-6, Bruce, Darlington)

28-element (Pickering)

Burnup ~ 7,500 MWd/t (nominal).

8,000 to 9,000 MWd/t for larger cores.

On-Line Refueling (8 to 12 bundles per day)

Approximates continuous refuelling.

Two independent shutdown systems.

SDS1 (shutoff rods), SDS2 (poison injection).

26


Aug. 25 – Sept. 3, 2010

On-power

Fueling

Modular

Design

Large heat

sinks

Heavy Water

Moderator and

Coolant

Simple fuel

bundle

Fuel

Calandria Tube

Pressure Tube

CANDU Reactor Technology

27


Aug. 25 – Sept. 3, 2010

CANDU-PHWR Features

Excellent neutron economy.

High conversion ratios (C.R.>0.8).

Operate on natural uranium (NU); enrichment not required.

High fuel utilization; conservation of resources.

Continuous On-line refuelling.

Low excess reactivity (~2000 pcm max); very little moderator poison.

Bi-directional fuelling; bi-directional cooling; more uniform burnup.

Higher fuel burnup for a given enrichment.

• 30% more burnup than 3-batch refuelling.

• Maximize uranium utilization (kWh/kg-U-mined).

High capacity factors (0.8 to 0.95).

Modular construction.

Pressure tubes; replaceable; reactor can be refurbished.

Local fabrication (do not need heavy forgings).

Refurbishment underway at Pt. Lepreau, Bruce, Wolsong CANDU reactors.

28


Aug. 25 – Sept. 3, 2010

CANDU Nuclear Steam Plant

29

Two heat transport

loops.

Bi-directional

cooling.

Bi-directional

fuelling.


Aug. 25 – Sept. 3, 2010

CANDU-PHWR Operational Issues

Plumbing

Feeders / headers for each PT.

Joints and seals.

Pressure tubes.

• Sag and creep.

• Corrosion, embrittlement (D, H).

• Periodic inspection and assessment.

Fuelling Machines

Maintenance; high radiation environment.

Tritium production (n + D T + )

Removal, handling, storage (T1/2 = 12.3 years).

• T He-3 + -

By-product uses: self luminous signs, fusion fuels, detectors.

• E.g. use T for fusion reactor experiments (ITER); He-3 for detectors.

30


Aug. 25 – Sept. 3, 2010

CANDU Safety Characteristics

Slightly positive coolant void reactivity (CVR).

Reactivity increases when coolant changes to void.

Due to slight shift in neutron energy spectrum.

Reduced resonance absorption in U-238.

What matters, is that the magnitude is relatively small.

Magnitude of reactivity coefficients should be as small as possible

• Whether positive, or negative.

But, there are several key mitigating circumstances.

Thermal-hydraulic design (2 separate heat transport loops).

Voiding is not usually instantaneous to all channels.

• Checkerboard voiding occurs first, reactivity increases more slowly.

Long neutron lifetime (~ 1 ms) in D2O also leads to slower transient.

• Plenty of time for engineered shutdown systems to work.

• Possibly more time than is available for shutdown and ECCS systems in

postulated LWR accident scenarios.

31


Aug. 25 – Sept. 3, 2010

CANDU Safety Characteristics

CANDU does well, by comparison to other reactor designs in postulated accident

scenarios involving reactivity initiated accidents (RIA‟s).

Longer neutron lifetime due to D2O moderator makes a big difference.

Lower rate of power increase.

Benchmark Postulated Accident Scenario Comparisons, by design:

CANDU-6

• Large Loss of Coolant Accident (LLOCA).

TMI-1 ( Babcock & Wilcox Pressurized Water Reactor)

• Main Steam Line Break (MSLB)

ESBWR (Economic, Simplified Boiling Water Reactor)

• Generator trip with steam bypass failure.

AP-1000 (Advanced PWR – Westinghouse)

• Rod ejection accident at hot full power (HFP), or hot zero power (HZP)

32


Aug. 25 – Sept. 3, 2010

CANDU During LLOCA

Peak fuel enthalpy for CANDU-6

under LLOCA:

~639 J/g

Pulse width longer.

Lower power increase rate.

Reduced chance of fuel

damage.

Peak fuel enthalpy in AP-1000

REA, HFP:

~758 J/g

Pulse width shorter.

Longer pulse width decreases

chance of fuel failure.

CANDU transient slower.

Longer neutron lifetime.

33


Aug. 25 – Sept. 3, 2010

CANDU Safety Comparable to LWR’s

Special CANDU features:

Shutdown systems operate in low-pressure environment.

• Multiple, independent shutdown systems (SDS1, SDS2).

• Very high reliability.

Auxiliary cooling by large heat sinks:

• D2O moderator, H2O shield tank.

Emergency Core Cooling (ECC)

• H2O in ECC acts as a neutron absorber, when it displaces D2O.

Key Reference:

A.P. Muzumdar and D.A. Meneley, “LARGE LOCA MARGINS IN CANDU

REACTORS - AN OVERVIEW OF THE COG REPORT”, Proceedings of

the 30th Annual Conference of the Canadian Nuclear Society, May 31 -

June 3, 2009.

34


Aug. 25 – Sept. 3, 2010

End of Lecture 1

See full version of main lecture presentation for additional

details and skipped slides.

See Supplement 1 and Supplement 2.

Research reactors, measurements, R&D.

Alternative concepts, prototypes, history.

See references, and suggested websites.

Questions?

35


Aug. 25 – Sept. 3, 2010

Schedule (Day 2)

Day 2

CANDU History (Gen-I, Gen-II) (optional, see slides/notes offline)

• NPD-2, Douglas Point

• Pickering, Bruce, Darlington, CANDU-6

Gen-III / Gen-III+

• Enhanced CANDU-6 (EC6), Advanced CANDU Reactor (ACR-1000)

• 220-PHWR (India), 540-PHWR (India), AHWR (India)

• TR-1000 (Russia) (optional, see slides/notes offline)

Gen-IV (optional, if time permits).

• SCOTT-R (old concept), CANDU-SCWR

Gen-V: ??? (optional, if time permits)

Additional Roles, International Penetration

Dominant Factors, Future Motivation

Conclusions

36


Aug. 25 – Sept. 3, 2010

CANDU History

NPD-2 (1962) (7-element fuel)

Douglas Point (1968), Gentilly-1 (1972-1977) (19-element)

KANUPP (1972, Pakistan) – See supplement 2.

RAPS 1,2 (India, 1973-1981) – See supplement 2.

Pickering A/B (1971-1986) (28-element fuel)

Bruce A/B (1976-1987) (37-element fuel)

Darlington (1990-1993) (37-element fuel)

CANDU-6 (37-element fuel)

Point Lepreau (1983), Gentilly-2 (1983)

Embalse (1984)

Wolsong (S. Korea, 1983-1999)

Cernavoda (Romania, 1996-2007)

Qinshan III (China, 2002-2003)

37


Aug. 25 – Sept. 3, 2010

CANDU HWR Evolution

Research, prototypes, commercial.

Gen III+

EC6

ACR-1000

Gen IV

CANDU-SCWR

38

Gen V

CANDU-X / HWR ???

India:

220-PHWR

540-PHWR

India:

700-PHWR

AHWR


Aug. 25 – Sept. 3, 2010

CANDU-6 (Canada, 1983-2007)

Single-unit Station

600 to 670 MWe net

380 channels, 12 bundles/channel.

37-element natural UO2 bundles.

Operations / Design Feedback

Pickering A/B, Bruce A/B.

Domestic and International Deployment

Point Lepreau, Gentilly-2

Argentina, S. Korea (4),

Romania (2), China (2)

39


Aug. 25 – Sept. 3, 2010

Gen III+ HWRs

Evolutionary design changes.

Various improvements on existing designs.

Monitoring, control systems.

Component materials and manufacturing.

Corrosion science, chemistry control.

Operations and maintenance, inspections.

Feedback from past experience (+50 years).

More modularity, standardization.

Reduced construction time, economies of scale.

Enhanced safety.

Better resource utilization; conservation of resources.

Aim for reduced capital, operational costs.

Aim for lower cost of electricity.

40


Aug. 25 – Sept. 3, 2010

Gen III+ HWR’s

EC6 (Enhanced CANDU-6)

Feedback from CANDU-6, Pickering, Bruce, Darlington, etc.

ACR-1000 (Advanced CANDU Reactor)

Feedback from CANDU-6, Pickering, Bruce, Darlington, etc.

Feedback from FUGEN (Japan), SGHWR (U.K.), Gentilly-1.

Feedback from LWR industry.

India‟s 220-MWe, 540-MWe, 700-MWe PHWR‟s

Evolutionary improvements on existing designs.

Similar to Douglas Point, Pickering, CANDU-6 designs.

AHWR (Advanced Heavy Water Reactor – India)

Extensive domestic R&D.

Feedback from domestic PHWR‟s (220-MWE, 540-Mwe class).

Some feedback from FUGEN, SGHWR?

41


Aug. 25 – Sept. 3, 2010

EC6 (Canada, Gen III+)

Enhanced CANDU-6 (EC6).

Retains basic features of CANDU-6 reactor.

700-MWe class reactor.

Good for both large and medium-sized markets.

Capable of daily load-following (100% 75% 100%), if necessary.

Evolutionary improvements over CANDU-6:

Target life up to 60 years, >90% capacity factor.

Modern steam turbines with higher efficiency and output.

• ~680 MWe (net) / 2064 MWth, 32% to 33% net efficiency.

Increased safety and operating margins.

Additional accident resistance and core damage prevention features.

• Addition of a reserve water system for passive accident mitigation.

A suite of advanced operational and maintenance information tools.

• SMART CANDU®.

Improved plant security and physical protection.

42


Aug. 25 – Sept. 3, 2010

EC6 (Canada, Gen III+)

Evolutionary improvements over CANDU-6 (continued):

Improved plant operability and maintainability.

• Overall plant design.

• Advanced control room design.

Improved severe accident response.

Advanced fire protection system.

Improved containment design features.

• Steel liner and thicker containment.

• Provide for aircraft crash resistance.

Reduced potential leakages following accidents.

Increased testing capability.

Construction schedule of 57 months achieved.

• By use of advanced construction methods.

• Total project schedule as short as 69 months.

43


Aug. 25 – Sept. 3, 2010

EC6 (Canada, Gen-III+)

44

Nuclear Power Plant


Aug. 25 – Sept. 3, 2010

ACR-1000 (Canada, Gen III+)

Advanced CANDU Reactor

Base on CANDU-6 design features

• Pressure tubes.

• Heavy water moderator.

• Short fuel bundles – online refueling.

• Multiple shutdown systems.

• Balance-of-plant similar, but higher steam P, T.

3187 MWth / 1085 MWe (net)

• Higher coolant pressure/temperatures

• ~34% net efficiency.

Modular construction, competitive design

Lower capital costs.

Local fabrication of components.

Lower-cost electricity.

45


Aug. 25 – Sept. 3, 2010


Special features

Light water coolant (11 MPa, 319 C)

• Reduced capital costs.

CANFLEX-ACR Fuel Bundle

• 43-element design; enhanced heat transfer.

• Enriched fuel (2 wt% to 3 wt%), central absorbing pin (Dy).

• Burnup: 20,000 MWd/t (nominal), extend with experience.

Tighter lattice pitch (24 cm); thicker pressure tubes, larger calandria tubes.

• More compact core; smaller reactor; higher power density.

• Lower moderator-to-fuel ratio.

• Negative coolant void reactivity.

Heavy water inventory reduced to ~ 1/3 of CANDU.

• Reduced capital costs.

Reactivity devices

• No adjusters.

• Liquid zone control (LZC) replaced: mechanical zone control (MZC) rods

46

Dr. Blair P. Bromley, Atomic Energy of Canada Limited (AECL) – Chalk River Laboratories

ACR-1000 (Canada, Gen-III+)

43-element CANFLEX fuel bundle

Same diameter and length as CANDU.

Greater subdivision for higher thermal margin (lower heat flux).

42 elements contain ~ 2 to 3 wt% LEU

• Uranium dioxide; Zr-4 clad.

Central poison element

• Yttrium-stabilised matrix

• ZrO2 + Dy2O3 + Gd2O3

• More neutron absorption during voiding.

Reference burn-up ~20,000 MWd/t

47


Aug. 25 – Sept. 3, 2010


ACR-1000 has higher power density.

~ same size as CANDU-6, but ~60% more power.

48


Aug. 25 – Sept. 3, 2010


49


Aug. 25 – Sept. 3, 2010


Special features

Safety systems

• Steel-lined large containment.

• Long-term cooling system to perform long term ECC and maintenance

cooling.

• High-pressure emergency feedwater system.

Severe accident prevention / mitigation.

• Reserve Water Tank for passive makeup to reactor cooling system,

steam generators, calandria and reactor vault.

• Moderator improved circulation.

• Purpose is to prevent / contain severe accident within the calandria.

50


Aug. 25 – Sept. 3, 2010


Multiple barriers – defense in depth

Fuel

• UO2 retains fission products.

• Zr-4 Clad.

Individual PT / CT channels.

Moderator tank.

Light water shield tank.

Concrete reactor vault.

Containment.

• Steel liner.

• Re-enforced Concrete.

Reserve water system.

• Gravity driven.

51


Aug. 25 – Sept. 3, 2010

India’s Gen III+ HWR Projects

PHWR

D2O-moderated, D2O-cooled pressure-tube reactors.

220-MWe, 540-MWe, 700-MWe class PHWR‟s.

Size options to fit local market requirements.

Similar to CANDU designs:

• Douglas Point (~220 MWe)

• Pickering (~540 MWe)

• CANDU-6 (~700 MWe)

But, evolutionary design improvements.

Advanced Heavy Water Reactor (AHWR)

Under current development in India.

Boiling light water coolant, thorium-based fuels.

General similarities to SGHWR, FUGEN prototypes.

• Fuel bundle design with many innovations.

52


Aug. 25 – Sept. 3, 2010

India’s Gen-III+ PHWR’s

Developed for smaller-sized markets.

220-MWe class PHWR.

Similar to Douglas Point CANDU design

Zr-2.5%Nb PT‟s.

19-element UO2 fuel bundles with bearing pads.

• 10 bundles per channel.

4 modern steam generator units.

540-MWe class PHWR.

Similar to Pickering CANDU design (390 channels).

• But with 37-element NU fuel bundles, 12 bundles/channel.

• 392 Channels, Zr-2.5%Nb PT, Zr-4 CT.

• 4 Vertical U-tube steam generators.

700-Mwe class PHWR

Based on India‟s indigenous 540-MWe PHWR design, with increased power

output, with some similarities to CANDU-6.

53


Aug. 25 – Sept. 3, 2010

India’s 220-MWe, 540-MWe PHWRs

Smaller-

sized

markets.

Modern

steam

generators.

Modern

steam

turbines.

54


Aug. 25 – Sept. 3, 2010

AHWR (India, Gen-III+)

Advanced Heavy Water Reactor

Prototype design under optimization and refinement.

Work continues on various design options.

Pu from PHWR, fast reactor, or spent LWR fuel.

U-233 from fast reactor, or self-sustaining.

Goals:

Advanced technologies required for Gen-III+

Demonstrate thorium fuel cycle technologies.

Fuel cycles with reduced environmental impact.

Heavy water moderated.

Boiling light water-cooled.

Steam to turbines at 6.8 MPa, 284 C.

920 MWth / ~300 MWe (net)

~32% efficient (for prototype).

452 vertical fuel channels, 61 control channels.

22.5-cm pitch, 54-element fuel assemblies.

55


Aug. 25 – Sept. 3, 2010


Hundred year design life of the reactor.

No exclusion zone beyond plant boundary required.

Heavy water at low pressure reduces potential for leakages.

Elimination of major components and equipment:

Primary coolant pumps and drive motors.

Associated control and power supply equipment.

Save electrical power.

SDS1: 37 shut off rods.

B4C rods.

SDS2: Liquid poison injection in moderator.

Lithium Pentaborate poison for shutdown.

24 Control Rods.

Passive (natural) shutdown system

Poison injection into moderator through valve actuated by increase in

steam pressure.

56


Aug. 25 – Sept. 3, 2010

AHWR Standard Fuel

Fuel: (U-233,Th)O2 + (Pu/Th)O2

~75% power from U-233 fission.

~20% power from Pu

~5% power from U-235

Burnup: ~38 GWd/t (average).

Inner Ring (12 pins)

3 wt% U-233 in Th.

Middle Ring (18 pins)

3.75 wt% U-233 in Th.

Outer ring (24 pins)

4.0/2.5 wt% Pu in Th.

Central displacer unit.

Central displacer rod.

Lower half of Zircaloy, upper half of SS.

Within Zircaloy tube which is filled with ECCS water.

57

(Th-Pu)MOX

Displacer unit

(Th-233U)MOX

ECCS water


Aug. 25 – Sept. 3, 2010

AHWR Standard Design

Burnup ranges from 33 to 48 GWd/t

3 burnup zones.

Average 38 GWd/t.

73 channels refuelled / year.

• ~1/6 of core / year.

Low Pu consumption

Annual Pu requirement 123 kg.

Annual U-233 requirement 163 kg

Deficit in U-233 by 22 kg (13.5%)

CVR from operating conditions:

-8 mk to -4 mk, varies with burnup.

SDS-1(35 SORs) meet the

shutdown margin in operating and

accidental conditions.

58


Aug. 25 – Sept. 3, 2010


Several fuel options for AHWR, flexibility:

Standard (Th,Pu)O2 cluster.

Mixed core of two cluster types (Th,Pu)O2 for U-233 self-sufficiency.

LEU in (U,Th)O2 clusters.

High burnups:

~38 GWd/t (Standard)

~35 GWd/t (Self-sufficient U-233)

~64 GWd/t (LEU)

Negative reactivity coefficients (fuel temperature, void coefficients).

Mined uranium requirement per unit energy is less for AHWR as compared

with alternatives.

Significant power fraction from U-233/Th-232:

75% (Standard)

66% (Self-sufficient U-233)

39% (LEU)

59


Aug. 25 – Sept. 3, 2010

Gen-IV HWR’s

Super-critical HWR

Super-critical coolant, not reactivity !

H2O at 25 MPa, 530 C to 625 C.

• D2O is an alternative coolant.

Not quite liquid, not quite vapor

45% to 50% net thermal efficiencies possible.

Early Concept:

SCOTT-R Reactor (1962), Westinghouse USA

Super Critical Once Through Tube Reactor

Today / Tomorrow:

CANDU-SCWR

Combine CANDU technology with supercritical H2O.

Parametric design studies underway.

60


Aug. 25 – Sept. 3, 201061

CANDU-SCWR (Canada, Gen-IV)

25 MPa, ~325 C inlet, 500 C to 625 C exit.

Direct Cycle, Efficiency ~ 45% to 50%.

>1000 MWe.


Aug. 25 – Sept. 3, 2010

CANDU-SCWR (Canada, Gen-IV)

CANDU Design features in CANDU-SCWR

Pressure tubes, with fuel bundles inside, or,

• Pressure vessel under consideration as well.

D2O moderator at lower temp. (~80 C).

• Auxiliary heat sink in case of postulated accident.

Design changes, options considered:

Tighter lattice pitch (22 cm to 27 cm).

Thicker pressure tubes (or a pressure vessel concept).

Vertical channels, instead of horizontal.

Once-through, or re-entrant tubes with insulator or

double wall between PT and fuel bundles.

Multi-batch off-line refuelling.

• Boron in moderator for excess reactivity hold down.

Fuel bundle modifications.

• Higher enrichment (materials, higher burnup).

• More pins (54 to 61) for enhanced heat transfer.

62


Aug. 25 – Sept. 3, 2010

Gen-V HWR’s ???

Advances in:

Materials science, manufacturing, process engineering.

Corrosion sciences, chemical engineering.

Isotope separation techniques.

Engineering design, computational analysis tools.

Balance of plant design, power conversion cycles.

Revisit old ideas postulated, tested, with modifications.

1950‟s, 1960‟s, etc.

Use D2O or alternative deuterated compounds as the moderator

for high-neutron economy; save neutrons.

Design goals

High thermal efficiency (>50%).

High conversion ratios, or thermal-breeding (e.g. with Th/U cycle).

High burnup / resource utilization.

Low long-term cost of electricity.

63


Aug. 25 – Sept. 3, 2010

Additional Future Roles for HWR’s

Advanced Fuel Cycles.

Synergism with LWR‟s and fast reactors.

• Integrated nuclear energy system.

Extending nuclear fuel utilization.

Breed/burn of U-233 from Th-232.

• Once-through-thorium (OTT), or,

• Self-sufficient equilibrium thorium (SSET).

Minimizing waste management issues.

• Burning of Pu and higher actinides.

Water Desalination

Fresh water is short supply world-wide.

Power for reverse-osmosis plants.

Waste heat for low-temperature distillation.

64


Aug. 25 – Sept. 3, 2010

Additional Future Roles for HWR’s

Hydrogen Production

High-temperature electrolysis.

Thermal/chemical processes.

Direct use in fuel cells for transportation, or,

Upgrading of low-grade hydro-carbon fuels.

• Coal, bitumen, biomass, peat.

o Synthetic gasoline, diesel, methanol, ethanol, etc.

High-temperature Steam

Enhanced recovery and upgrading of hydrocarbons

• Oilsands, coal

Role for alternative HWR designs to produce very high-

temperature steam.

• CANDU-SCWR, gas-cooled HWR‟s.

65


Aug. 25 – Sept. 3, 2010

International Penetration of HWR’s

World installed and operating nuclear capacity (2009):

439 Reactors, ~375 GWe net

World installed HWR capacity (2009):

48 Reactors, ~25 GWe net

20 Reactors in Canada, ~15 GWe net

28 HWR abroad

• India (17), South Korea (4), China (2), Romania (2), Argentina (2),

Pakistan (1)

HWR‟s: ~11% of reactors, ~7% of net power

Current commercial HWR‟s tend to be smaller in size:

~200 MWe to ~900 MWe

But, ACR-1000 is sized (~1085 MWe, net) for larger markets.

66


Aug. 25 – Sept. 3, 2010

Argentina (1)

Canada (20)Romania (2)

India (2)Pakistan (1)

South Korea (4)

China (2)

CANDU Reactors Around the World

67


Aug. 25 – Sept. 3, 2010

Why are HWR’s not the Dominant

Technology Today?

Partly Historical / Competing Technologies.

Cost of producing D2O.

Graphite much cheaper, although not as good a moderator.

• Pathway initially chosen by other nations:

o U.K. (Magnox, AGR), France (GCR), Russia (RBMK).

Weapons/Defence and Naval programs.

Development of industrial infrastructure for uranium enrichment.

• U.S.A., Russia, U.K., France, China.

Use of PWR‟s for naval submarines, and aircraft carriers.

• Unique application for which PWR‟s well-suited.

• Compact cores, simple reactor design.

• Cost of fuel is not a concern for defence budget.

Large investment in LWR technology.

• Major head start on alternatives.

• BWR technology benefited from R&D for PWR‟s.

68


Aug. 25 – Sept. 3, 2010

Why are HWR’s not the Dominant

Technology Today?

Uranium supplies available and cheap (for now)

Canada, Australia, U.S.A., Kazakhstan, Africa, etc.

Enriched uranium supplies assured (for now)

Important for Europe, Japan, Korea.

Recycled and down-blended HEU from weapons programs.

Competing Technologies (LWR‟s).

Resources to support more than one or two technologies limited.

Many countries switched / focused on LWR technology.

• U.S.A., Russia:

o Knowledge and experience base is large.

• France, Germany, Sweden, Switzerland, Belgium, etc.

• Czech, Slovakia, Ukraine, Taiwan.

• Japan, S. Korea; others have followed suit

U.K.: Magnox and AGR‟s were performing well in 1970‟s.

• Technical difficulties; now seeking standardization for new reactors.

69


Aug. 25 – Sept. 3, 2010

Motivating Factors to Use more

HWR’s in the Future

Fuel Costs.

As uranium demand increases and cost goes up.

High conversion ratios become important.

HWR design variants will be advanced converters.

• Possibly more cost effective than using Fast Breeders alone.

Need to exploit alternative fuels:

• Recycled uranium, plutonium from LWR‟s.

• Thorium fuel cycle (breeding and burning U-233).

Integrated Reactor Systems.

HWR‟s complementary to LWR‟s and Fast Reactors.

• Extending fissile and fertile fuel resources with high CR.

• Burning of Pu and Actinides from spent fuel of LWR‟s and FR.

• Minimizing spent fuel and waste for long-term storage.

70


Aug. 25 – Sept. 3, 2010

Motivating Factors to Use more

HWR’s in the Future

Next-generation Designs.

Gen-IV and beyond.

Issues for large pressure vessels.

• Manufacturing challenges, availability, local fabrication.

Modular design with pressure tubes more feasible.

• Particularly for super-critical-water coolant designs.

Renewed motivation to use super-critical water, organic, gas, liquid

metal, or molten salt coolants.

• To achieve high thermal efficiencies ~50%

• PT design with maximum neutron economy possible.

Use of thermal neutron spectrum is attractive.

• Lower fuel enrichment required than in a fast reactor.

• Longer neutron lifetime, especially in a D2O reactor, is an enhanced

safety feature.

71


Aug. 25 – Sept. 3, 2010

Conclusions

Heavy Water Reactor Advantages.

Excellent neutron economy, better utilization of resources.

Special safety features:

• Large heat sink, multiple shutdown systems, longer neutron lifetime.

Modular construction (pressure tubes)

• Local manufacturing.

On-line refuelling high capacity factors, higher fuel utilization.

Flexibility for fuel and coolant types.

Technology Improvements.

Reducing cost of D2O using advanced separation technologies

Better materials, sealing, less corrosion, easier maintenance.

• Similar goals for other technologies.

Improving thermal efficiencies (alternative coolants).

72


Aug. 25 – Sept. 3, 2010

Conclusions

International Interest in Heavy Water Reactors

Canada – main focus: mature technology / commercialized

• Technology development since 1945.

• CANDU design development; CANDU-6 exported abroad.

• EC6 and ACR-1000 are Gen-III+ designs, with reduced capital costs.

India – long-term interest with large supplies of thorium

• PHWR‟s patterned after / similar to Canada.

• Independent / domestic technology development.

o Pressure tube reactors inherently modular.

• AHWR is India‟s next-generation design.

o Conserve uranium resources; maximize utilization.

73


Aug. 25 – Sept. 3, 2010

Conclusions

International Interest in Heavy Water Reactors

China – growing interest

• Use of CANDU-PHWR for advanced fuel cycles.

• Recycled uranium (RU), depleted uranium (DU), thorium.

o Already testing natural uranium equivalent (NUE) fuel bundles

made from RU and DU in Qinshan reactors.

• Investigating CANDU-SCWR technology for long-term.

Germany, U.K., Japan, France, Sweden, U.S.A, etc.

• HWR prototypes developed and tested in past.

• Resources to develop and sustain alternative technologies limited.

o Focus on LWR‟s to save money in short-term.

• Secured supply of cheap uranium has put focus on LWR technology,

but this could change in the future, as world demand for nuclear

energy increases.

74


Aug. 25 – Sept. 3, 2010

Conclusions

Future for HWR Technology

Reducing capital costs; improving efficiencies.

Use of enriched fuel; alternative coolants.

Complement other technologies (faster breeders, LWR‟s, etc.)

• Spent fuel from LWR‟s could be used in HWR‟s.

• Exploitation of thorium-based fuels.

Increasing cost of fuel favors HWR technology.

Increasing role for HWR‟s in nuclear energy supply

World demand for nuclear energy growing.

Keeping several options open is prudent.

HWR‟s are an important part of the nuclear energy mix.

• Today, and even more so in the future.

Plenty of business for everyone.

75


Aug. 25 – Sept. 3, 2010

End of Lecture 2

See extended version of main lecture for more details and

skipped slides.

Also see Powerpoint presentations for:

Supplement 1

Supplement 2.

For further reading:

See suggested references.

See suggested websites.

76


Aug. 25 – Sept. 3, 2010

Frederic Joliot / Otto Hahn

Summer School

Visit www.fjohss.eu

77

http://www.fjohss.eu/

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